4017
Inorg. Chem. 1992, 31, 4017-4018
Kinetics of Iron(III) Reduction by Hemoglobin and Its Isolated a-Subunits Bruce R. Van Dyke,' Louis Kitten, Jack Hegemuer, and Pad Saltman Department of Biology, University of California, San Diego, La Jolla, California 92093-0322
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Received October 25, 1991 Hb has long been assigned the principal responsibilityof oxygen transport and delivery but more recently has been shown to act as a reducing Rifkind observed that Fe(II)-Hb02 can r+uce Cu(I1) through cys-93 on the p - ~ h a i n . ~Eguchi .~ and Saltman further characterized the kinetics and mechanisms of both Cu(I1) and Fe(II1) This study extends the previous kinetic work by quantitating differences in the ability of tetrameric Hb ( ~ ~ 2 8 2and ) its isolated a-subunits to reduce Cu(I1) and Fe(II1) complexes.
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l/[FeNTA] (mM-') Figure 1. Double-reciprocal plot of initial velocities of Fe reduction by Hb ( 0 ) and a-subunits (0). Each point is the mean of three kinetic experiments with CV
